Catalytic conversion of hydrocarbons



Patented Aug. 31, 1954 CATALYTIC CONVERSION OF HYDROCARBONS Rufus Burnell Bennett, Baytown, Tex., assignor,

by mesne assignments, to Standard Oil Development Company, Elizabeth, N. J a corporation of Delaware N Drawing. Original application June 28, 1949,

Serial No. 101,901. Divided and this application March 23, 1950, Serial No. 151,538

6 Claims.

The present invention is directed to a dehydrogenation catalyst and a method for dehydrogenating hydrocarbons employing the same. More particularly, the invention is directed to the dehydrogenation of parafiinic hydrocarbons.

This application is a division of U. S. Serial No. 101,901 entitled Catalyst and Method for Employing Same filed June 28, 1949, now U. S. Patent No. 2,648,639, in the name of Rufus 13. Bennett.

Prior to the present invention it has been known to dehydrogenate hydrocarbons and many catalysts and processes therefor have been suggested by workers in this field. The dehydrogenation of olefins to diolefins does not present an appreciable problem; however, the dehydrogenation of paraffins to olefins is not so simple since the yields obtainable are low and the conversion of the parafiinic hydrocarbons as well as selectivity to the desired olefin are also low. Furthermore, the high temperature treatment necessary for the formation of olefins from paraffins requires a catalyst which is rugged and unsusceptible to attrition and decomposition due to the excessive temperatures necessary to cause substantial conversion of the parafinic hydrocarbon to the olefinic hydrocarbons.

It is, therefore, the main object of the present invention to provide a new catalyst suitable for dehydrogenation of paraffinic hydrocarbons to olefinic hydrocarbons.

Another object of the present invention is to provide a rugged and heat resistant catalyst which may be used in dehydrogenating parafiins to olefins.

A still further object of the present invention is to provide a catalyst comprising oxygen-containing compounds of calcium and manganese.

Still another object of the present invention is to provide a process in which paraffinic hydrocarbons are dehydrogenated to olefinic hydrocarbons by contact with an improved catalyst.

The objects of the present invention may be achieved by forming a catalyst composition comprising a major portion of a carrier consisting substantially of aluminum oxide and minor portions of oxygen-containing compounds of calcium and manganese and contacting a heated hydrocarbon such as a paraifinic hydrocarbon with the catalyst at an elevated temperature and pressure under conditions to form a product and recovering the product.

The present invention may be described briefly as a composition comprising a base material of aluminum oxide in a major amount and a catalarly a paraffinic hydrocarbon feed is contacted with the improved catalyst under conditions to form a product containing a substantial amount of the dehydrogenated hydrocarbon which is then removed from contact with the catalyst and the dehydrogenated hydrocarbon recovered therefrom.

The catalyst composition of the present invention, as stated before, comprises a major amount of aluminum oxide and minor amounts of oxygencontaining compounds of calcium and manganese. The major amount of aluminum oxide will ordinarily comprise no less than 58% of the catalyst composition, while the minor amounts of oxygen-containing compounds of calcium and manganese may contain respectively calcium calculated as calcium oxide in an amount in the range between 1.4 and 14% by weight of the composition and manganese calculated as manganese oxide in the range between 5.6 and 28% by weight of the composition. The calcium and manganese may be present in the composition either in the form of the calcium manganate or in the form of calcium oxide and manganese oxide. A preferred composition consisting of 20% calcium manganate and aluminum oxide gives satisfactory results in dehydrogenating parafl'lns.

The aluminum oxide employed in the present invention may contain a small amount of water. In fact an amount of water in the aluminum oxide in the range from 1% to 5% by weight may exert a beneficial effect. As examples of aluminum oxide, those containin 1.4% by weight of water and of 4 to 8 mesh in particle size and those containing 3.4% water and passing mesh perform satisfactorily in the present invention. In order to illustrate the invention further an improved catalyst in accordance with the present invention was prepared from Ca(NOs)z, MnOz. and A1203. 325 parts of A1203, 119 parts of Ca(NO3)z, 43.7 parts of MnOz and parts'of distilled water were placed in a jar mill and mulled for 20 hours. The resulting mixture was ed in the presence of air for 30 minutes at 300 F. and thereafter the temperature was ,in-,

creased 100 F. every 15 minutes until a temperature of 800 F. was reached; after 15 minutes at 800 F. the temperature was raised rapidly to 1250 F. and maintained at this temperature for approximately 3 hours. The dried and heated catalyst, as described, was then allowed to cool to 230 F. and was then formed into inch tablets prior to employment as hydrocarbon conversion catalyst according to the present invention. The aforesaid catalyst composition contained approximately 20% calcium manganate and approximately 80% aluminum oxide. This catalyst was placed in a reactor vessel which was heated to a temperature of 1095 F. Normal heptane at a feed rate of one volume of feed per volume of catalyst per hour was then contacted with the heated catalyst at 1095 F. and at atmospheric pressure. A conversion of 54% of the feed was obtained, with 28% selectivity to olefins. The yield obtained was 15.4% by volume (based on the feed) of olefins and 6.1% by volume of arcmatics. 3.7% by weight of carbon was produced in this operation.

It will be noted from the foregoing run that the improved catalyst composition allowed the production of over 15% by weight of olefins which is considered a very good yield from the paraffinic hydrocarbon. It will be further noted that the dehydrogenation operation was conducted at atmospheric pressure and in the absence of extraneously added hydrogen. Introducing hydrogen with the feed and employing operating pressures up to 150 p. s. i. g. may result in the efiect of markedly reduced carbon formation without adversely affecting olefin selectivity. Thus, it is contemplated that the present invention may be carried out at temperatures from l075 up to 1400 F. and at pressures from to about 150 p. s. i. g., feed rates from about 0.3 to about volumes of feed per volume of catalyst per hour and hydrogen in an amount from 0 to 3000 standard cubic feet of hydrogen per barrel of naphtha feed.

The carbon deposited on the catalyst may be periodically removed by burning with air employing process .cycles from about 1 to about 3 hours under normal operations. However, by introducing steam with the naphtha feed, longer process cycles may be obtained up to as much as 3000 hours with the carbon being removed practically continuously through the water gas reaction which is caused to proceed by the introduction of steam with the feed hydrocarbon.

While the present invention has greatest utility in dehydrogenating parafiinic to olefinic hydrocarbons it may also be used in the so-called hydroforming process in which naphthene hydrocarbons are converted or hydroformed to aromatic hydrocarbons; when such operations are conducted it may be desirable to use lower temperatures in the range from about 900 to 1200 F., pressures in the range given and with hydrogen being added extraneously. The invention is also adapted to the conversion of olefins to diolefins and under these conditions it may be desirable to employ higher temperatures in the range given with the introduction of steam with the olefinic hydrocarbon feed to promote the water gas reaction.

The hydrocarbons employed as feed stocks may comprise the butanes, butylenes, pentanes, pentylenes, methylcyclopentanes, cyclohexane, methylcyclohexane, hexanes, heptanes, octanes, and other representative olefinic, paraffinic, and naphthenic hydrocarbons.

While the invention has been described and illustrated by reference to employing substantially pure hydrocarbons of the several types mentioned, the invention is not restricted thereto, but may be employed on a mixture of hydrocarbons. For example, if a mixture of hydrocarbons comprising paraflinic and naphthenic hydrocarbons in the gasoline boiling range is charged the net effect would be to dehydrogenate the parafflns and naphthenes to produce olefins and aromatics which would result in a substantial improvement in octane rating of the gasoline.

The invention has been described and illustrated by reference to a catalyst comprising a major portion of aluminum oxide. It is to be clearly understood that I may employ aluminum oxide in its various commercial forms available on the market and that the alumina may contain other materials besides aluminum oxide. Exam ples of alumina finding use in the present invention may be found in U. S. 2,217,013 issued to Grosse et al., October 8, 1940.

The nature and objects of the present inven tion having been fully described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

1. A method for improving the octane number of a mixture of parafiinic and naphthenic hydrocarbons in the gasoline boiling range which comprises heating a stream ofa gasoline containing naphthenic and paraffinic hydrocarbons to a temperature in the range of 900 to 1400 F., contacting the heated gasoline with a catalyst comprising a major portion of aluminum oxide no less than 58% by weight and minor portions no less than 7% by weight and no more than 42% by weight, respectively of oxygen-containing compounds of calcium and manganese in the range between 1.4% and 14% by weight and in the range between 5.6% and 28% by weight calculated, respectively, as calcium and manganese oxides at an elevated pressure to convert same and form a product having an appreciated octane number, and recovering said product.

2. A method of dehydrogenating hydrocarbons which comprises heating a stream of a hydrocarbon susceptible to dehydrogenation to a temperature in the range from 900 to 1400 F., contacting the heated hydrocarbon with a catalyst comprising a major portion of aluminum oxide no less than 58% by weight and minor portions no less than 7% by weight and no more than 42% by weight respectively of oxygen-containing compounds of calcium and manganese in the range between 1.4% and 14% by weight and in the range between 5.6% and 28% by weight calculated, respectively, as calcium and manganese oxides at an elevated pressure to dehydrogenate same and form a product, and recovering said product.

3. A method for dehydrogenating paraflinic hydrocarbons which comprises heating a paraffinic hydrocarbon having at least 4 carbon atoms in the molecule to a temperature in the range between 1075 and 1400 F., contacting said heated hydrocarbon with a catalyst comprising a major amount approximately by weight of aluminum oxide and a minor amount approximately 20% by weight of calcium manganate at an elevated pressure to dehydrogenate said parafiinic hydrocarbon and form a product, and recovering said product.

4. A method in accordance with claim 3 in which the parafl'inic hydrocarbon is heptane.

5. A method in accordance with claim 3 in an elevated pressure to dehydrogenate said paraffinic hydrocarbon and form a product, and recovering said product.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,148,140 Tropsch Feb. 21, 1939 2,184,235 Groll et a1. Dec. 19, 1939 

2. A METHOD OF DEHYDROGENATING HYDROCARBONS WHICH COMPRISES HEATING A STREAM OF A HYDROCARBON SUSCEPTIBLE TO DEHYDROGENATION TO A TEMPERATURE IN THE RANGE FROM 900* TO 1400* F., CONTACTING THE HEATED HYDROCARBON WITH A CATALYST COMPRISING A MAJOR PORTION OF ALUMINUM OXIDE NO LESS THAN 58% BY WEIGHT AND MINOR PORTIONS NO LESS THAN 7% BY WEIGHT AND NO MORE THAN 42% BY WEIGHT RESPECTIVELY OF OXYGEN-CONTAINING COMPOUND OF CALCIUM AND MANGANESE IN THE RANGE BETWEEN 1.4% AND 14% BY WEIGHT AND IN THE RANGE BETWEEN 5.6% AND 28% BY WEIGHT CALCULATED, RESPECTIVELY, AS CALCIUM AND MANGANESE OXIDES AT AN ELEVATED PRESSURE TO DEHYDROGENATE SAME AND FORM A PRODUCT, AND RECOVERING SAID PRODUCT. 